Poly Bag Sealing Machine

Thickness is the part people forget

A thin courier bag and a heavy poly liner are both 'poly bags' and they are not the same job. Thin film seals almost instantly and burns through if the setting is too long. Heavy film needs more heat and more dwell, and on a machine set for thin bags it will come out looking sealed and pull apart in the hand.

If you seal both - and many units do, thin bags for despatch and heavy liners for bulk - say so on the enquiry. A machine that can be set for both is a different conversation from one that lives at a single setting.

Width, and the two-pass problem

Measure your widest bag flat across the mouth and buy a seal bar longer than that. This is the single most common ordering mistake in this category.

What happens when you get it wrong is that wide bags are sealed in two overlapping passes. The overlap is where it leaks, and a customer who receives a bag with a double seal across the top can see that a corner was cut. On a courier or e-commerce bag, where the pack is the first thing the buyer touches, that matters more than it does in a godown.

Which format for which bench

Poly bag work splits neatly by volume, and the four formats map onto it.

• A shop counter or a small despatch desk - a hand sealer. One hand holds the bag, the other presses.
• Filled bags of loose goods - a foot sealer, because a full poly bag will not stay square with one hand off it.
• A despatch bench running all shift - a table top machine, built for that duty.
• An e-commerce packing line at scale - a continuous band sealer, and it will pay for itself in operator time rather than in film.

Poly bags that need something else

A few poly bag jobs are not sealer jobs at all. A bag that has to keep air out needs a vacuum machine; a bag that has to be tamper-evident to a customer's satisfaction usually needs a printed tape or a security bag rather than a heat seal; and a gusseted liner too thick to fuse cleanly may be better closed with a tie or a strap.

We would rather tell you that than sell you a machine you will stop using.

Buying bags on a roll instead of pre-made

A poly bag operation reaches a point where pre-made bags stop making sense. Every size has to be stocked, the fastest-moving one runs out first, and you are paying somebody to make and count bags you could make as you go.

The alternative is layflat tubing on a roll. You cut the length you need, seal one end, fill it and seal the other. One roll covers every length, stock goes from six sizes to one, and the cost per bag falls.

It changes what you should buy. A machine with a cutting wire alongside the sealing element trims the excess in the same press, which is what makes the method quick rather than fiddly. Without it you are cutting separately and the saving disappears into labour.

It is worth doing the arithmetic before you order the machine rather than after, because the two decisions are really one. Tell us at the enquiry whether your bags come pre-made or on a roll.